This invention relates to an arrangement and method of achieving a dial pulse muting function in a register sender PABX system.
In present day PABX systems using direct drive (no register senders), the dial springs of the telephone short the receiver so that pulsing is not heard by the originating station. However, in register sender PABX systems, particularly those which must receive a full digit before sending pulses forward on a trunk, it is possible for the dial springs to return to normal and for the receiver to be across the loop when the sender is outpulsing. In such cases, the outpulsing will be heard by the originator. In a copending U.S. patent application, Ser. No. 614,407, filed on Sept. 18, 1975, by Donald W. McLaughlin, said application and the present application both being assigned to the same assignee, there is disclosed a PCM PABX system in which such a situation could exist. In the system disclosed in this copending application, dial pulses are accumulated and stored by the software in the central processor and a full digit must be received before it is outpulsed to the central office. After a delay of approximately 300 miliseconds, during which time the dial pulses are being accumulated, the sender outpulses the full digit. If the trunk circuit is sampled at this time, these dial pulses are fowarded through the system to the time switch (a memory). Subsequently, these dial pulses are returned to the subscriber's line circuit and will be heard by the subscriber. It is preferred that these dial pulses not be heard.
Accordingly, it is an object of the present invention to provide an arrangement and method for providing a dial pulse muting function in register sender PABX systems for preventing sender outpulsing from being heard.